1. Field of the Invention
The present invention generally relates to a socket connector having conductive contact elements for electrically connecting an electronic package, such as a central processing unit (CPU) module, to a circuit board, and more particular to a socket connector having compactly arranged contact elements. A method for making the socket connector is also disclosed.
2. The Related Arts
Socket connectors for mounting an electronic package, such as a central processing unit (CPU) module, to a circuit board are well known and commonly used in the computer industry. FIG. 1 of the attached drawings shows an example of the socket connectors that is referred to as ZIF (Zero Insertion Force) socket connector. The socket connector, generally designated with reference numeral 10, comprises a dielectric base housing 12 defining an array of cavities 14 open to a top face 15 of the base housing 12. A dielectric cover 16 rests on the top face 15 of the base housing 12 and is movable across the top face 15 of the base housing 12 in a given moving direction A. The cover 16 defines through holes 18 corresponding to the open cavities 14 of the base housing 12. The cover 16 carries an electronic package 20 having depending pin legs 22 extending through the holes 18 and partially projecting into the cavities 14. An actuator 24 drives the cover 16 in the moving direction for bringing the pin legs 24 into contact with conductive contact elements 26 received and retained in the base housing 12 thereby forming electrical connection therebetween. Examples of socket connectors of this type are disclosed in U.S. Pat. Nos. 4,498,725, 5,833,483, 6,059,596, 6,142,810, and 6,159,032.
U.S. Pat. No. 4,988,310 also discloses a socket connector of this type. The device of the ""310 patent comprises a base housing 12 defining cavities 14 each receiving a contact element having a single beam. An example of the single-beam contact element is shown in FIG. 2 of the attached drawings wherein a contact element 26 is stamped from a metal plate (not shown) and remains attached to a carrier strip 28 after stamping. The carrier strip 28 carries a number of contact elements 26 for simultaneously fitting the contact elements 26 into the cavities 14 of the base housing 12. The carrier strip 28 is then removed to complete the manufacture of the connector.
Each contact element 26 comprises a retention section 30 retained in the cavity 14 of the base housing 12 and a post 32 extending beyond the base housing 12 for being soldered to a circuit board (not shown). An intermediate section 34 extends from the base section 30 and is substantially opposite to the post 32. The intermediate section 34 has a distal free end 36 from which a cantilever beam 38 extends for biasingly engaging the pin leg 22 of the electronic package 20.
Also referring to FIG. 3, the cantilever beam 38 comprises a free end portion 40 and an oblique portion 42 connected to the intermediate section 34 and the free end portion 40 by two bend portions 44 whereby the free end portion 40 is substantially parallel to but offset from the distal end 36 of the intermediate section 34 a distance determined by the oblique portion 42.
The cavity 14 of the base housing 12 that receives the contact element 26 has a side wall 46 parallel to and opposite to the free end portion 40 of the cantilever beam 38 with a gap therebetween. The pin leg 22 is initially received in the cavity 14 at a position corresponding to the distal end 36 of the intermediate section 34 and is moved in the moving direction A under the guidance of the oblique portion 42 into the gap between the free end portion 40 and the side wall 46. The cantilever beam 38 is deflected as shown in dashed lines and thus biasingly engages the pin leg 22.
A disadvantage of the conventional contact elements is that the contact elements 26 must be lined up and in registration with each other because the cantilever beam 38 extends in a direction substantially parallel to the moving direction A of the pin leg 22. The pitch between adjacent cavities 14 of the base housing 12 must be at least greater than the length of the cantilever beam 38. In addition, due to the need of the oblique portion 42 for biasingly engaging the free end portion 44 with the pin leg 22, the overall length of the cantilever beam 38 cannot be effectively reduced. Thus, the overall size of the socket connector with the same arrangement and same number of contact elements cannot be reduced and the contact elements cannot be arranged in a compact manner.
Thus, a socket connector that allows the contact elements to be compactly arranged is desired.
An object of the present invention is to provide a socket connector having compactly arranged contact elements.
Another object of the present invention is to provide a method for manufacturing a socket connector having compactly arranged contact elements.
To achieve the above objects, in accordance with the present invention, a socket connector comprises a base housing defining cavities and contact elements positioned in the cavities. Each cavity has a first channel extending in a given direction and a second channel oblique with respect to and in communication with the first channel. Each contact element comprises a retention section retained in the cavity and oblique with respect to the given direction. The contact element comprises a cantilever beam somewhat complaint with the given direction. A pin leg of an electronic package is initially received in the second channel of the cavity and movable in the given direction toward and biasingly engaging the cantilever beam. The contact element comprises a straight tail extending beyond the housing with a mass of solder attached thereto for soldering to a circuit board. A slot is defined in the tail for securely retaining the solder.
A method for making the socket connector of the present invention comprises the steps of (1) providing a base housing defining cavities having first and second channels oblique with respect to each other; (2) forming a row of contact elements connected to a carrier strip by connection sections; (3) twisting the connection sections to obliquely orient the contact elements with respect to the carrier strip; and (4) gang loading the contact elements into the cavities with the cantilever beams of the contact element somewhat compliant with the given direction.